Confederates vs. Indians vs. Union vs. etc

I didn’t know that some Indian tribes got involved in the Civil War. I’ve been reading a history of the Indian wars recommended by one of youse, and was surprised to see that at the outbreak of the war, several chiefs in Oklahoma sided with the Union, including Sonuk Mikko, AKA “Billy Bowlegs,” shown here. They fought Confederates in December 1861. Mikko eventually became a captain in the Union Army’s Indian Home Guard and fought in several more battles.

Nor did I know that some Confederate PoWs were allowed to enlist in the Union Army, which sent six regiments of them west to fight Indians. The clunky term for them was “galvanized Yankees.”

So: Pro-Union Indians were fighting Confederates who, after being captured, agreed to fight other Indians for the Union? What a country.